heavy water

In article <3mgsde$kn6 at agate.berkeley.edu>
frauwirt at notmendel.Berkeley.EDU (Ken Frauwirth (BioKen)) writes:
> In article <hooftznfgyo6wtt66 at nu.EMBL-Heidelberg.DE>,
> Rob Hooft <hooft at EMBL-Heidelberg.DE> wrote:
> >>>>>> Phillip Bigelow writes:
> >
> > Phillip> Trumborm at dc37a.nci.nih.gov (Mark W. Trumbore) writes:
> >
> > Mark> The formual for heavy water is D2O (D = deuterium). You have to
> > Mark> consume a huge amount of heavy water for it to be toxic.
> >
> > Phillip> What would be the symptoms? Also, would consuming
> > Phillip> air/water/food that contains pure O18 (heavy oxygen) also be
> > Phillip> pathologic?
> >
> >The only difference between H2O and D2O is the fact that the D atoms are
> >2 times as heavy as the H atoms, and thus a number of processes involving
> >those (essential to the energy systems in the body) would run 1.4 times
> >slower (square root of two, "kinetic isotope effect"). I would think this
> >will lead to imbalance quite soon, but it could be that Mark is correct.
> >
>> Since the vast majority of the water in the body is functions mainly as a
> solvent, there would be little effect of heavy water on the body. In order
> to see any imbalance, most of the normal water would have to be replaced
> with heavy water, and this would require a huge amount to be ingested.
> Also, most processes involving hydrogen (electron transfer, etc.) use
> hydrogen removed from food metabolites, rather than from water, and these
> would still be normal "light" hydrogen.
>
Now this is an interesting thread...
Doing a MedLIne search on "oral and D2O" gives an interesting list of
articles. Including articles about checking infant metabolism by
feeding them D2O. Also, hypertensive rats actually seem to do better
after 6 weeks on 30/70 D2O/H2O. I didn't actually find anything where
they managed to kill anything, but it sounded like 60/40 D2O/H2O over
long periods actually started to get kindof toxic...